Document shredders are used to destroy documents (i.e. files) having confidential content. By such documents should primarily be understood (paper) sheets, but also binders, diskettes, CDs or other data carriers.
For the destruction, i.e. for the shredding of the documents, a document shredder has a motor-operated cutting unit, which dissects the document to be shredded. For this, the document shredder has a document feeder and a container which receives the dissected documents.
One problem with document shredders consists in the fact that these can be overloaded by the introduction of over-thick documents, in particular of too many sheets. In order to forestall an overload which is harmful to the document shredder and to prevent a paper jam or paper blockage, ordinary document shredders automatically shut down at a predetermined load limit value, i.e. they shut off the drive of their cutting unit and, where necessary, trigger a reversing operating mode, by which the drive direction of the motor is reversed and by which the document to be shredded is fed back out.
In addition, it is known from the prior art to equip document shredders with a turbo mode, in which the torque of the motor driving the cutting unit is increased.
DE 195 25 027 A1 shows, for example, a document shredder, the cutting unit of which is driven by a drive motor configured as a capacity motor having an operating capacitor. In the event of an overload of the drive motor of the cutting unit, said drive motor is operated for a short time in reversing operating mode and switched off. After this, an auxiliary capacitor, which can be connected in parallel to the operating capacitor of the drive motor, is briefly switched on, preferably for one document passage, whereby the torque of the drive motor can be increased.
On said document shredder, it is disadvantageous that, if the drive motor is overloaded, a turbo mode is in any event activated by connection of the auxiliary capacitor. In many cases, a manual removal of the paper from the document shredder may however be more appropriate. It should here also be borne in mind that the connection of the auxiliary capacitor leads to an—even if only temporary present—overstraining and heating of the drive motor, but also of the drive transmission and of the cutting unit. The turbo mode should thus be activable only in exceptional cases.
Examples of document shredders are disclosed in U.S. Pat. Nos. 7,721,982 and 6,116,528, U.S. Patent Publication Nos. US20100187341 and US20120001001, and German Patent Publication No. DE19525027A1. The disclosures of these and all other publications referenced herein are incorporated by reference in their entirety for all purposes.
Advantages of the present disclosure will be more readily understood after considering the drawings and the Detailed Description.